1. Field of the Invention
The present invention relates to a printing apparatus for printing an image by discharging ink on a sheet.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 3-151239 discusses an inkjet printing apparatus in which a heater for drying the moisture in ink applied onto a sheet is mounted. The heater is controlled so that the sheet has an optimum surface temperature according to the image recording duty (hereinafter, “duty”), i.e., the amount of ink applied per unit area of the sheet.
When an image region having a low duty that is easily dry and an image region having a high duty that is easily dried are intermingled with each other, if temperature control that is optimal for the low duty portion is performed, it is impossible to sufficiently dry the high duty portion. Conversely, if temperature control that is optimal for the high duty portion is performed, the low duty portion is excessively heated, so that the sheet can deform or degrade.
Japanese Patent Application Laid-Open No. 3-151239 discusses a technique in response to the problem in which the apparatus has a plurality of heaters in divided regions to control the respective heaters based on the duty, thereby the temperature is controlled for each region.
However, in the apparatus discussed in Japanese Patent Application Laid-Open No. 3-151239, when the temperature setting of a given heater is greatly different from the temperature setting for an adjacent heater, it is difficult to achieve a desired temperature because the portion near the edge of the heater is affected by the adjacent heater. Consequently, the above-described problem cannot be resolved.